Telephone-exchange system.



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TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JULY 15,1915- 1 Patented Nov, 2?, 191?.

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CHARLES L. GOODRUM, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO

WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Nov. 2?, with Application filed July 15, 1915. Serial No. 39,996.

To all whom it may concern:

.Be it known that I, CHARLES L. Gooononr, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to circuit arrangements for selector switches employed in automatic telephone systems.

The object of this invention is to provide a simple and eflicient circuit arrangement for selector switches and to reduce the number of the circuit controlling apparatus.

It has been the practice in such selector circuits to employ a timing means, such as a slow-acting relay, for controlling the change-over, 2'. 6., the connecting into circuit of the secondary magnet after the completed operation of the primary magnet, another function of this slow-acting relay being to control the operation of the releasing mechanism for the selector switch.

According to one feature of this invention, a plurality of operating magnets of the selector switch, for instance, the primary magnet and the release magnet, are arranged in such a manner-that the operation of one of said magnets, for instance that of the release magnet, is prevented during the operation of another one of said magnets, for instance the primary magnet, no additional mechanisms or relays being provided for this purpose. By this arrangement only the regular operating magnets and the impulse receiving mechanism or line relay are associated with the selector switch for controlling the operation thereof, whereas heretofore it was necessary to provide, in addition to the above mentioned apparatus, one or more relays for successfully controlling the Ioperation of a selector switch. In a preferred embodiment of this invention the primary and release magnets are connected in parallel, the simultaneous operation of the magnets being prevented by making the latter slow-acting and by providing a resistance in the divided branch of the circuit including the release magnet.

According to another feature of this invention, an operating magnet, such as the secondary magnet of the selector switch, has

an operating and a locking circuit. Upon the closure of the operating circuit the magnet, by mterrupting its own circuit, causes the selector to hunt for an idle outgoing line, such as a trunk leading to another switching mechanism, and as soon as an idle trunk is seized, the locking circuit of the magnet is closed preventing its further operation.

Other new and useful features of this invention will appear from the following description and the appended claims.

The drawings represent a circuit arrangement of an automatic telephone exchange system, only so much being shown of the apparatus and circuits as 1s necessary for a clear understanding of the invention.

As the operation and mechanical construction of the switches and other apparatus employed in the building up of a connection are well known in the art, in the following a detailed description will be given only of the circuits of a selector switch employed in the establishment of a connection between a calling and a called line.

Upon the removal of the receiver from the switch-hook at substation 1, a trunk finder 2 is operated in the well-known manner to select an idle trunk leading to a selector switch 3. After the brushes of the trunk finder 2 have been set, a circuit is closed from grounded battery 4, through the left-hand winding of a line relay 5, wiper 6 of a side switch associated with selector 3, the line circuit of substation 1, side-switch wiper 7, and right-hand winding of relay 5, to ground. Relay 5 becomes energized and closes a circuit from ground through its armature and front contact, side-switch wiper 10, the winding of a slow acting escapement magnet 11, and side-switch wiper 12, to grounded battery 13, and magnet 11 upon energization causes the side-switch wipers to move into position 2.

The calling subscriber at substation 1 proceeds now to cause the setting of selector 3, and for this purpose he interrupts for a short period of time, the substation line circuit a desired number of times by operating a calling device 14: provided at substation 1. In response to each short circuit interruption line relay 5 releases its armature and closes a circuit which is divided in two branches. This divided circuit may be traced from ground through armature and back contact of relay 5, and then on Ill) ' net 22 does notbecome energized.

pose ofzresistance 201111 series with the WlllClngof lnagnet .22 is to more definitely prevent the actuation of release magnet 22 during the operation of line relay 5 (vibration of the armature).

The escapement magnet 11 became ener gized upon the first release of the armature of line relay 5, the circuit being closed from grounded battery 13 through side-switch wiper 12, the winding of escapement magnet 11, side-switch wiper 10 and the back contact and armature of line relay 5, to ground. Escapement magnet 11 being slow to release is maintained energized during the vibration of the armature of line relay 5. However, in position 2 of the side switch, the wipers are not moved into the next position upon, the energization, but upon the deenergization of magnet 11. This deenergi- .zation of escapement magnet 11 occurs after the impulses havebeen sent out and line relay 5 is maintained energized, interrupting at its back contact the circuit of magnet ll.

Upon the escapement of the side-switch wipers into position 3, a circuit is closed from ground through the armature and front contact of line relay 5, side-switch wiper 2a, the back contact, armature and the winding of a secondary magnet 25, to grounded battery 26. Magnet 25 interrupts its own circuit at its back contact and causes the stepping of the brushes of selector 3 in a vertical direction. The selector brushes are stepped until the terminals of an idle trunk are reached. Such idle trunks are I characterized by a ground'connection to their test terminals 30, no such ground being connected to the test terminals of busy trunks. As shown in the drawings, ground may be connected to terminal 30 through the armature and back contact of a line relay 32 associated with a switching mechanism employed in the establishment of a connection between the calling substation 1 and a called substation 33. As soon as the test terminal 30 (these terminals being connected in multiple) of an idle trunk is reached, a circuit is closed from ground through the armature and back contact of relay 32, terminal 30, test brush 34 of selector 3, side-switch wiper 10, the winding 0f escapement magnet 11, side-switch wiper 12, and the front. contact armature and winding of magnet 25, to grounded battery its brushes on the terminals of the selected idle trunk.

Upon the closure of this circuit, escapement magnet 11 also becomes energized and causes the stepping of the sideswitch wipers into position 4, in which position the calling, substation line is extended through side-switch wipers .6 and 7e and the brushes of selector 3 to other switching mechanisms employed in the establishment of a connection to the called substation In this positionof the side switch the circuit of relay 5 and the locking circuit of magnet 25 is opened atside-switch wiperso, 7 and 10, 12 respectively, and magnet 25 does not find another energizing circuit upon the release of its armature, side-switch wiper 24L being new inposition 4. While the selector brushes are traveling over terminals of busy trunks, clue to the lack of ground connection to test terminals 30 (for instance it line relay 32 is energized), the above traced circuit for escapement magnet 11 and stepping magnet 25 cannot be established.

Upon the severing V of the 7 connection, ground is connected through the armature and back contact of relay 32 to the conductor leading to test terminal 30, this ground being disconnected during conversation in the same manner as the ground at the armature. of relay 5 is disconnected from switch 2 at sideswitch wiper 15. A circuit is ,now established from ground through selector brush 31L, side-switch wiper 21 and the winding of release n1agnet'22, to grounded battery, 23. Magnet 22 closes a locking circuit for itself from ground through a contact (closed as soon as selector 3 leaves its normal position),

and the front contact, armature and winding of magnet 22, to grounded battery 23. Under the control of magnet 22, selector 3 and the associated side switch are restored to normal position, the locking circuit ofmagnet 22 remaining closed until selector 3 is restored to normal. When the side-switch associated with selector?) reaches its normal position, side-switch wiper 15 closes a circuit from ground, right hand armature and 'back contact of line relay 5, side-switch wiper 15 to terminal 36, on which brush '37 of trunk finder 2 rests, to the releasing mechanism of the trunk finder, causing thereby the release of this switch in thewellknown manner.

If the subscriber at substation l abandons the call before or after the sending out of impulses, 2'. e., when the-side-switch wipers V are in position 2, due to the release of the armature of line relay 5, the circuit extending from ground through the armatureand back contact of this relay, side-switch wiper 10, resistance 20, side-switch Wiper 2i and the winding of release magnet 22 to grounded battery 23, is closed for a long period, and therefore the release magnet, which did not become energized during the vibration of the armature of line relay 5, will operate now and will cause the release of the selector 3 and the associated side switch.

In case the call is abandoned during trunk hunting, 2'. 6., while magnet 25 is operating in position 3 of the side switch, upon the release of relay 5, a circuit is closed from ground through the armature and back con.- tact of relay 5, side-switch wiper 21 and the winding of release magnet 2:2, to grounded battery 23, causing the release magnet to perform .its function.

What is claimed is:

1. In a telephone exchange system, incoming lines and outgoing lines, a selector switch for extending a calling incoming line to an idle outgoing line, a motor magnet for said selector switch, two circuits for said motor magnet, means for closing one of said circuits and means for opening the other one of said circuits upon the seizure of an idle outgoin line by said selector switch.

2. In a telephone exchange system, incoming lines and outgoing lines, a selector switch for extending a calling incoming line to an idle outgoing line, a motor magnet for said selector switch, an operating and a locking circuit for said motor magnet, means controlled by said motor magnet to interrupt said operating circuit, means for closing said locking circuit upon the seizure of an idle outgoing line by said selector, and means operative thereupon for definitely opening said operating circuit.

8. In a. telephone exchange system, incoming lines and outgoing lines, a selector switch for extending a calling incoming line to an idle outgoing line, an electromagnet for operating said selector switch; an armature for said eleotromagnet, an energizing circuit for said electromagnet leading through a back contact of said armature, a locking circuit for said electromagnet leading through a front contact of said armature, and means for closing said locking circuit upon the seizure of an idle outgoing line by said selector switch.

In witness whereof, I hereunto subscribe my name this 10th day of July A. D., 1915.

CHARLES L. GOODRUM.

topics of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). 0. 

